Figure 1. Zhongjianosaurus compared to Mei long, a scansoriopterygid bird. Both have relatively short forelimbs vs. long hind limbs among other traits.

Xu and Qin report,“The distal carpal is represented by the compound ‘semilunate’ carpal, formed by the addition of distal carpal 4 on its ventrolateral corner, and this morphology also is present in the troodontid Mei long (Xu et al., 2014a).”

Well, Mei long is indeed a troodontid, but so are all birds. Better to label it a scansoriopterygid bird to avoid confusion.

When you read the PDF, bear in mindthat the authors do not label the manual digits 1–3, but 2–4 as they pay homage to Limusauruswith what I call digit 0.

Perhaps if the pelvis or skull was preservedin Zhongjianosaurus it would nest elsewhere. At present shifting Zhongjianosaurus to Microraptor adds 6 steps. Shifting Zhongjianosaurus to Velociraptor adds 9 steps. With the given data set and character list, this is how it all shakes out at present. And, you have to admit, it’s a pretty good match!

ReferencesXu X; Qin Z-C 2017. A new tiny dromaeosaurid dinosaur from the Lower Cretaceous Jehol Group of western Liaoning and niche differentiation among the Jehol dromaeosaurids” (PDF). Vertebrata PalAsiatica. In press.

Updated November 10, 2016 with higher resolution images of the specimen. The new data moved the taxon over by one node.

Not published yet in any academic journal,but making the news in the popular press in Germany to promote a dinosaur museum (links below) is the geologically oldest Archaeopteryxspecimen (no museum number, privately owned?). Found by a private collector in 2010, the specimen has been declared a Cultural Monument of National Significance. It is 153 million years old, several hundred thousand years older than the prior oldest Archaeopteryx. It is currently on display at a new museum, Dinosaurier-Freiluftmuseum Altmühltal in Germany, about 10 kilometers from where the fossil was found.

Figure 1. The new oldest Archaeopteryx in situ with color tracings of bones. The ilium has been displaced to the posterior gastralia, or is absent. I cannot tell with this resolution.

Figure 1b. Archaeopteryx 12 in higher resolution.

So is it also the most primitive Archaeopteryx?No. But it nests as the most primitive scansioropterygid bird. As we learned earlier, the Solnhofen birds formerly all considered members of the genus Archaeopteryx (some of been subsequently recognized by certain authors as distinct genera) include a variety of sizes, shapes and morphologies (Fig. 3) that lump and separate them on the large reptile tree. The present specimen has been tested, but will not be added to the LRT until it has a museum number or has been academically published (both seem unlikely given the private status). Given the additional publicity the specimen is now in the LRT.

The fossil is wonderfully complete and articulated
and brings the total number of Solnhofen birds to an even dozen.

This just inBen Creisler reports, “The fossil specimen was originally found in 2010 in fragmented condition and took great effort to prepare and piece together as it now appears.”

Figure 2. Reconstruction of the geologically oldest Archaeopteryx, now nesting at the base of the Scansoriopterygidae. Note the large premaxillary teeth and short snout on a relatively small skull.

Compared to other Archaeopteryx specimensyou can see the new one is among the smallest (Fig. 3) and has a distinct anatomy.

Figure 2. Several Archaeopteryx specimens. The geologically oldest one, (at bottom) is among the smallest and most derived, indicating an earlier radiation than the Solnhofen formation.

Figure 1. Omnivoropteryx reconstructed from X-ray photographs (Figs. 2, 3) Some workers think this bird looks like an oviraptorid. I think it looks like an anurognathid.

From the Wikipedia article“Omnivoropteryx (meaning “omnivorous wing”) is a genus of primitive flying bird from the early Cretaceous Upper Jiufotang Formation of China.

Figure 2. The Omnivoropteryx skull X-ray with DGS color tracings. These were used to reconstruct the skull in lateral view.

“The authors who described Omnivoropteryx, Stephen Czerkas and Qiang Ji, stated that their specimen closely resembles Sapeornis (Fig. 5), but the pubis was longer and, since no skull was known for Sapeornis, they did not consider the two names synonyms. The later discovery of Sapeornis skulls shows that they were indeed similar to Omnivoropteryx. This may make Omnivoropteryx a junior synonym of Sapeornis, and the name may be abandoned.”

Now that you can see
the two taxa together, do you agree that they are conspecific? BTW, they nest in separate clades in the large reptile tree.

Figure 3. Omnivoropteryx shares the plate with parts of another bird.

Omnivoropteryx was preserved
with parts of another bird (Fig. The only data I have found comes from an X-ray.

Figure 4. Epidexipteryx, another scansoriopterygid with a bird-like pelvis. The toes are not known.

Epidexipteryx (Fig. 4) is a sister
to Omnivoropteryx. Both share a long third finger. Omnivoropteryx also has a long fourth toe. Unfortunately sister taxa do not preserve the toes. This clade produced some anurognathid mimics.

Figure 5. Sapeornis does not nest as a sister to Omnivoropteryx.

Sapeornis
is basal to living birds. The scansoriopterygid clade, of course, became extinct.

The line between birds and theropod dinosaurs
has become increasingly fuzzy now that so many non-birds have feathers and other former bird-only traits.

This is a good sign
that evolutionary theory embraces: small changes and a gradual accumulation of traits in derived taxa.

Ultimately
it may come down to a single defining trait (like mammary glands in mammals, or alternatively a squamosal/dentary jaw joint when soft tissue is missing) when you have lots of taxa near the base of a new major clade. So what is that trait? Or what are those traits as recovered by the large reptile tree?

The basal bird and its proximal outgroup
At present the last common ancestor of all extant birds, scansoriopterygids and enantiornithes in the large reptile tree. is the Thermopolis specimen of Archaeopteryx(Fig. 1). The original authors (Mayr et al. 2007; Rauhut 2013) did not employ a phylogenetic analysis, so perhaps did not realize what they had.

For now
the pre-bird theropod, Eosinopteryx(Fig.1) nests just basal to the basal bird theropod, Archaeopteryx. You might find it interesting to see which traits differentiate the latter from the former in the large reptile tree. This list, short as it is, is by no means complete. It simply reflects the general characters used for all reptiles in the large reptile tree.

Figure 1. Eosinopteryx, a pre-bird, compared to Archaeopteryx, a basal bird to scale. Click to enlarge.

Archaeopteryx (Thermopolis) novelties vs. Eosinopteryx

Frontal/parietal suture straight and > than frontal/nasal suture

Metacarpals 2-3 subequal

Pubis and ischium oriented posteriorly (convergent with some deinonychosaurs)

Pedal 4 subequal to metatarsal 4 (convergent with some deinonychosaurs)

Pedal 2.1 not > p2.2

Metatarsal 5 shorter than pedal digit 5 (all vestigial, of course)

Figure 2. The coracoid of the Thermopolis specimen is not as elongate as in the more derived taxa. It is just barely not a disc. Thus, this basal taxon was not quite the flapper as the other Solnhofen birds.

Unfortunately
none of these traits are unique to the bird clade.

I thought, perhapsthat an elongate and locked down coracoid (the key to the origin of flapping) would prove to be present in all basal birds. Such a coracoid is indeed present in other specimens of Solnhofen birds, but not in the Thermopolis specimen (Fig. 2), the basalmost example.

So what we are seeing
in these six Solnhofen birds are discrete steps in the evolution of the flapping behavior, necessary for creating thrust and ultimately flight, as in many living birds. Just as in Late Jurassic pterosaurs, the island/lagoon environment of Solnhofen was as powerful an agent as the Galapagos islands at splitting basal birds into various clades.

From the Mayr et al. abstract on the Thermopolis specimen:“We describe the tenth skeletal specimen of the Upper Jurassic Archaeopterygidae. The almost complete and well-preserved skeleton is assigned to Archaeopteryx siemensii Dames, 1897 and provides signiﬁcant new information on the osteology of the Archaeopterygidae. As is evident from the new specimen, the palatine of Archaeopteryx was tetra-radiate as in non-avian theropods, and not triradiate as in other avians. Also with respect to the position of the ectopterygoid, the data obtained from the new specimen lead to a revision of a previous reconstruction of the palate of Archaeopteryx. The morphology of the coracoid and that of the proximal tarsals is, for the ﬁrst time, clearly visible in the new specimen. The new specimen demonstrates the presence of a hyperextendible second toe in Archaeopteryx*. This feature is otherwise known only from the basal avian Rahonavis and deinonychosaurs (Dromaeosauridae and Troodontidae), and its presence in Archaeopteryx provides additional evidence for a close relationship between deinonychosaurs and avians**. The new specimen also shows that the ﬁrst toe of Archaeopteryx was not fully reversed but spread medially, supporting previous assumptions that Archaeopteryx was only facultatively arboreal*. Finally,we comment on the taxonomic composition of the Archaeopterygidae and conclude that Archaeopteryx bavarica Wellnhofer, 1993 is likely to be a junior synonym of A. siemensii****, and Wellnhoferia grandis Elzanowski, 2001 a junior synonym of A. lithographica***** von Meyer, 1861.”

* Actually not as prominent as in deinonychosaurs. Such a toe works just as well at climbing tree trunks as climbing dinosaur flanks.

**This may be a convergence as the two clades are separated by taxa without a hyper extensible pedal 2.

*** Perhaps facultatively able to perch, but arboreality would have been a precursor behavior.

**** These two are sisters in the large reptile tree.

***** These two are not sisters.

Other traits in the Theromopolis specimen
visible in Figure 1 not present in the large reptile tree include the following:

Mayr et al. looked at pedal digit 2
and noticed it was capable of hyperextension (Fig. 3). They likened it to pedal digit 2 in deinonychosaurs (Fig. 4) which is famous for its ability to elevate the ‘killer claw’.

On a final note:
Mayr et al. (2007) report four premaxillary teeth in the Thermopolis specimen. I think they might have missed counting the anteriormost premaxillary tooth (Fig. 6) bringing the total to five.

Updated October 23, 2015 with modifications to the ectopterygoids from data beneath the mandibles..

Cathayornis yandica (Zhou et al. 1992, Figs. 1-3, IVPP V9769) was an Early Cretaceous enantiornithine bird known from a virtually complete skeleton on plate and counter plate. It is crushed flat.

The best published tracings
of this specimen are shown here (Fig. 1). I wonder if you’ll agree there is too much left to the imagination in both of these professional tracings. The easy parts are correctly labeled, but I sense confusion in the more difficult details. Some of these were labeled originally with a “?”.

Figure 1. Previous best efforts at tracing Cathayornis. Above, Tracing of Cathayornis from Zhou et al. 1992. Below tracing of Cathayornis skull by O’Connor and Dyke 2010 traced using camera lucida. Some element labels are guesses (See “?”). A few are mistakes.

Try DGS just once to see if it works for you.
Applying color overlays to digital images of Cathayornis (Fig. 2, 3) recovers more bones more accurately than prior efforts (Fig. 1). And these can be used in reconstructions (Fig. 3). Note the postorbital and squamosal both drifted over the right frontal. That was a surprise. Yes, a tiny postfrontal is present, not fused to the frontal. Broken bones can be identified and repaired. Even the palatal bones can be identified.

Figure 2. Cathayornis skull animated GIF. Each frame lasts 5 seconds. Here virtually all skull elements are identified and applied to the reconstruction in three views (below). Compare the results of this technique to figure 1. Note how the upper and lower jaws match curves.

There is no guarantee you’re going to get things right the first time.
I don’t get things right the first time. I make changes as the interpretation runs its course. All DGS does is to remove some of the confusion inherent in the roadkill by segregating one bone after another until most – or all – of the bones are accounted for and fit the reconstruction while matching the patterns of sister taxa.

The postcrania
of Cathaysaurus is traced here (Fig. 3) and used to create a reconstruction in several views. The furcula can be traced here. Originally it was overlooked and misidentified.

Figure 3. Cathayornis tracing and reconstruction from tracing. Boxed area are ventral and rib elements originally segregated on a distinct layer and offset here for clarity. Note the green furcula, overlooked originally. Those green bones on either side of the sternum are considered part of the sternum in traditional works. Perhaps they are, but the visible one appears to overlay the sternum, rather than be a part of it.

It may just be a matter of applied effort
When you discover something in paleontology, all you have to do is unveil it. The discovery is the big deal. Not much effort is required, but it is always appreciated. Later workers can add details with appropriate levels of support and criticism. If I had access to the specimen or a higher resolution image, perhaps the level of accuracy would increase further.

Now I’ll ask of the bird people
what I ask of the pterosaur people. Try to build a reconstruction. It helps when you realize there are parts missing and then you can apply more effort to look for that part in the specimen itself.

If I have made any mistakes here, please bring them to my attention. I’m no bird expert, but I’m learning as I go. Here is a new image of enantiornithine birds to scale (Fig. 4) including Sulcavis, which we looked at recently.

Figure 1. Click to enlarge. Pre-bird and bird sternae. Note the replacement of the sternum with gastralia in Sulcavis.

Ever since the adventof the dual sternae in Velociraptor and kin, and of the single sternum in Archaeopteryx (Fig. 1), most birds had/have an ossified sternum. One exception is the enantiornithine bird, Sulcavis (Fig. 1-4).

Sulcavis geeorum (O’Connor et al. 2013, Early Cretaceous, BMNH Ph-000805) is a robin-sized enantiornithes with a relatively small skull and, remarkably, no sternum. Teeth with grooved enamel radiating from the tips gave it its name (sulcus = groove). That was seen as the most distinctive feature. A sternum replaced by gastralia was not considered an issue (see below).

Soft tissue
Although the specimen includes some soft tissue, O’Connor et al. report one pubis missing and another present only proximally. The ischium was reported missing. My examination identifies areas were both pubes (green) and ischia (magenta) used to be (Fig. 2).

Proximal humerus rises dorsally and ventrally to centrally on the concave head

Metacarpal 3 longer than mc2

Distal tarsals fused to metatarsals, but metatarsals unfused distally

Figure 3. Sulcavis reconstruction. PILs on foot. Note the lack of a sternum. The pedal ungual length and curvature indicate an arboreal lifestyle.

Unfortunately, none of theses traits are listed as characters in the large reptile tree, yet Sulcavis nests with Cathayornis sharing the following traits distinct from other birds:

Skull not shorter than cervicals

Posterior quadrate straight

More than 4 premaxillary teeth

Posterior mandible deeper anteriorly

Retroarticular descends

Metatarsals 2-3 aligned with 1

Pedal 2.2 > p2.1

More pertinent taxa would reduce this list.

Figure 4. Sulcavis skull as originally interpreted (above) and traced using the DGS method (middle) to create a reconstruction (below). Note, several bones here were not originally identified. It looks possible that a substantial mandibular fenestra might have been present.

Due to the contrived problem
of digit identification in birds and bird-like theropods described and falsified here, O’Connor et al. describe the three manual digits as the

alular digit

major digit

minor digit

Such renaming of digits 1-3 is totally unnecessary.

Re: The sternum
O’Connor et al. report, “No direct information regarding the morphology of the sternum is preserved.” That’s because there is no sternum in this taxon (Figs, 1, 2). The gastralia run right up to the coracoids. So, does this taxon appear to demonstrate how the sternum in enatiornithine birds is formed? Yes, by enlarging and fusing the gastralia, not as a new single, complete bone.

Sternae also appear in dromaeosaurs and oviraptors by convergence. Twin sternae in these taxa do not appear to be homologous with the single sternum of birds. A single sternum originates as a small bone, wider than long followed by a long set of gastralia extending to the pubis, distinct from large twin sternae.

Figure 1. Jim Clark putting his best interpretive spin on the weird vestigial hand of Limusaurus. Click to play.

I ran across this YouTube video featuring Dr. Jim Clark talking about his then new ceratosaur dinosaur, Limusaurus, which we looked at earlier here. Clark addresses the importance of the hand of Limusaurus, which he claims with admirable confidence that this was a ‘transitional’ theropod that demonstrates how digit 1 was lost, digit 2 took on the appearance of digit 1, digit 3 took on the appearance of digit 2 and so on. That’s called a ‘phase shift’ as one digit takes on the identify of the one next to it and it is gaining wide acceptance, despite its bizarre premise.

That same hypothesis
is echoed here online at the Varagas Lab and it is becoming the standard paradigm on theropod hands. As an example, the recent paper on Haplocheirus labeled the three manual digits 2, 3 and 4.

This all started
with a report on chicken embryo hands by Thulborn and Hamely (1984), Thulburn (1993) and Burke and Feduccia (1997). Before then everyone labeled the three digits of theropod hands, 1, 2 and 3, which was eminently logical. Shortly after the Burke and Feduccia study workers struggled against the new hypothesis, but recently (following the publication of Limusaurus) have rallied to support this hypothesis in papers appearing online here and here and here.

This isn’t the first time Occam’s razor was ignored.We’ve already seen several very odd paradigms arise in paleontology. A forelimb launch for giant pterosaurs is one such boondoggle. The extra bone in the wing of Yi qi is another. The nesting of Vancleaveaand pterosaurs with archosauriformes are yet other examples. There are dozens of others. The theropod finger ‘phase shift’ is one more false paradigm that keeps spreading and needs to be stopped.

As discussed earlier, chicken embryos develop an extra medial finger as embryos. This finger bud ultimately disappears by the time of hatching. It is a relic from our basal tetrapod ancestry, from a time when our ancestors had six or more fingers. This has nothing to do with the normal count of five fingers in all post-Devonian tetrapods. We all develop through an embryonic stage when our hands are webbed mittens. In only one adult animal that we know of, Limusaurus, did this extra medial finger appear in an adult — and only because the hand of Limusaurus is a tiny vestige that stopped developing normally. Essentially it’s an embryo hand that retained the medial bud.

This one key fact
has been overlooked by other workers who have flocked to the ‘phase shift’ hypothesis. Which is the simpler explanation: 1) all the fingers suddenly appear like their neighbor finger, changing phalanx counts, or 2) an embryonic bud appears then disappears before hatching.

There is always a simple explanation
for every seemingly magical event or paleontological problem. The six-fingered ancestry of chickens is a key fact overlooked by modern theropod paleontologists who apparently are content to just count the fingers. Sometimes it’s not what you see that counts, but what experience you bring to what you see that trumps logic-busting arguments.

In theropods, what you see is what you get.
Fingers 1, 2 and 3 are indeed fingers 1, 2 and 3. In embryos you may see another medial digit, but it’s not homologous with the medial digit in any other tetrapod, except Limusaurus, as noted above. There is no phase shift of theropod fingers.

ReferencesBurke AC and Feduccia A 1997. Developmental patterns and the identification of homologies in the avian hand. Science 278: 666–668.Thulborn RA and Hamley TL 1984. ON the hand of Archaeopteryx. Nature 311:218.Thulborn RA 1993. A tale of three fingers: Ichnological evidence revealing the homologies of manual digits in theropod dinosaurs. New Mexico Museum of of Natural History and Science Bulletion 3:461-463.